[linux.git] / crypto / lrw.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* LRW: as defined by Cyril Guyot in
 *	http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
 *
 * Copyright (c) 2006 Rik Snel <[email protected]>
 *
 * Based on ecb.c
 * Copyright (c) 2006 Herbert Xu <[email protected]>
 */
/* This implementation is checked against the test vectors in the above
 * document and by a test vector provided by Ken Buchanan at
 * http://www.mail-archive.com/[email protected]/msg00173.html
 *
 * The test vectors are included in the testing module tcrypt.[ch] */

#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>

#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>

#define LRW_BLOCK_SIZE 16

struct priv {
	struct crypto_skcipher *child;

	/*
	 * optimizes multiplying a random (non incrementing, as at the
	 * start of a new sector) value with key2, we could also have
	 * used 4k optimization tables or no optimization at all. In the
	 * latter case we would have to store key2 here
	 */
	struct gf128mul_64k *table;

	/*
	 * stores:
	 *  key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
	 *  key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
	 *  key2*{ 0,0,...1,1,1,1,1 }, etc
	 * needed for optimized multiplication of incrementing values
	 * with key2
	 */
	be128 mulinc[128];
};

struct rctx {
	be128 t;
	struct skcipher_request subreq;
};

static inline void setbit128_bbe(void *b, int bit)
{
	__set_bit(bit ^ (0x80 -
#ifdef __BIG_ENDIAN
			 BITS_PER_LONG
#else
			 BITS_PER_BYTE
#endif
			), b);
}

static int setkey(struct crypto_skcipher *parent, const u8 *key,
		  unsigned int keylen)
{
	struct priv *ctx = crypto_skcipher_ctx(parent);
	struct crypto_skcipher *child = ctx->child;
	int err, bsize = LRW_BLOCK_SIZE;
	const u8 *tweak = key + keylen - bsize;
	be128 tmp = { 0 };
	int i;

	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
					 CRYPTO_TFM_REQ_MASK);
	err = crypto_skcipher_setkey(child, key, keylen - bsize);
	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
					  CRYPTO_TFM_RES_MASK);
	if (err)
		return err;

	if (ctx->table)
		gf128mul_free_64k(ctx->table);

	/* initialize multiplication table for Key2 */
	ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
	if (!ctx->table)
		return -ENOMEM;

	/* initialize optimization table */
	for (i = 0; i < 128; i++) {
		setbit128_bbe(&tmp, i);
		ctx->mulinc[i] = tmp;
		gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
	}

	return 0;
}

/*
 * Returns the number of trailing '1' bits in the words of the counter, which is
 * represented by 4 32-bit words, arranged from least to most significant.
 * At the same time, increments the counter by one.
 *
 * For example:
 *
 * u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
 * int i = next_index(&counter);
 * // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
 */
static int next_index(u32 *counter)
{
	int i, res = 0;

	for (i = 0; i < 4; i++) {
		if (counter[i] + 1 != 0)
			return res + ffz(counter[i]++);

		counter[i] = 0;
		res += 32;
	}

	/*
	 * If we get here, then x == 128 and we are incrementing the counter
	 * from all ones to all zeros. This means we must return index 127, i.e.
	 * the one corresponding to key2*{ 1,...,1 }.
	 */
	return 127;
}

/*
 * We compute the tweak masks twice (both before and after the ECB encryption or
 * decryption) to avoid having to allocate a temporary buffer and/or make
 * mutliple calls to the 'ecb(..)' instance, which usually would be slower than
 * just doing the next_index() calls again.
 */
static int xor_tweak(struct skcipher_request *req, bool second_pass)
{
	const int bs = LRW_BLOCK_SIZE;
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct priv *ctx = crypto_skcipher_ctx(tfm);
	struct rctx *rctx = skcipher_request_ctx(req);
	be128 t = rctx->t;
	struct skcipher_walk w;
	__be32 *iv;
	u32 counter[4];
	int err;

	if (second_pass) {
		req = &rctx->subreq;
		/* set to our TFM to enforce correct alignment: */
		skcipher_request_set_tfm(req, tfm);
	}

	err = skcipher_walk_virt(&w, req, false);
	if (err)
		return err;

	iv = (__be32 *)w.iv;
	counter[0] = be32_to_cpu(iv[3]);
	counter[1] = be32_to_cpu(iv[2]);
	counter[2] = be32_to_cpu(iv[1]);
	counter[3] = be32_to_cpu(iv[0]);

	while (w.nbytes) {
		unsigned int avail = w.nbytes;
		be128 *wsrc;
		be128 *wdst;

		wsrc = w.src.virt.addr;
		wdst = w.dst.virt.addr;

		do {
			be128_xor(wdst++, &t, wsrc++);

			/* T <- I*Key2, using the optimization
			 * discussed in the specification */
			be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
		} while ((avail -= bs) >= bs);

		if (second_pass && w.nbytes == w.total) {
			iv[0] = cpu_to_be32(counter[3]);
			iv[1] = cpu_to_be32(counter[2]);
			iv[2] = cpu_to_be32(counter[1]);
			iv[3] = cpu_to_be32(counter[0]);
		}

		err = skcipher_walk_done(&w, avail);
	}

	return err;
}

static int xor_tweak_pre(struct skcipher_request *req)
{
	return xor_tweak(req, false);
}

static int xor_tweak_post(struct skcipher_request *req)
{
	return xor_tweak(req, true);
}

static void crypt_done(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->data;

	if (!err) {
		struct rctx *rctx = skcipher_request_ctx(req);

		rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
		err = xor_tweak_post(req);
	}

	skcipher_request_complete(req, err);
}

static void init_crypt(struct skcipher_request *req)
{
	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	skcipher_request_set_tfm(subreq, ctx->child);
	skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
	/* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
	skcipher_request_set_crypt(subreq, req->dst, req->dst,
				   req->cryptlen, req->iv);

	/* calculate first value of T */
	memcpy(&rctx->t, req->iv, sizeof(rctx->t));

	/* T <- I*Key2 */
	gf128mul_64k_bbe(&rctx->t, ctx->table);
}

static int encrypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	init_crypt(req);
	return xor_tweak_pre(req) ?:
		crypto_skcipher_encrypt(subreq) ?:
		xor_tweak_post(req);
}

static int decrypt(struct skcipher_request *req)
{
	struct rctx *rctx = skcipher_request_ctx(req);
	struct skcipher_request *subreq = &rctx->subreq;

	init_crypt(req);
	return xor_tweak_pre(req) ?:
		crypto_skcipher_decrypt(subreq) ?:
		xor_tweak_post(req);
}

static int init_tfm(struct crypto_skcipher *tfm)
{
	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
	struct priv *ctx = crypto_skcipher_ctx(tfm);
	struct crypto_skcipher *cipher;

	cipher = crypto_spawn_skcipher(spawn);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	ctx->child = cipher;

	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
					 sizeof(struct rctx));

	return 0;
}

static void exit_tfm(struct crypto_skcipher *tfm)
{
	struct priv *ctx = crypto_skcipher_ctx(tfm);

	if (ctx->table)
		gf128mul_free_64k(ctx->table);
	crypto_free_skcipher(ctx->child);
}

static void free(struct skcipher_instance *inst)
{
	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	kfree(inst);
}

static int create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct crypto_skcipher_spawn *spawn;
	struct skcipher_instance *inst;
	struct crypto_attr_type *algt;
	struct skcipher_alg *alg;
	const char *cipher_name;
	char ecb_name[CRYPTO_MAX_ALG_NAME];
	int err;

	algt = crypto_get_attr_type(tb);
	if (IS_ERR(algt))
		return PTR_ERR(algt);

	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
		return -EINVAL;

	cipher_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(cipher_name))
		return PTR_ERR(cipher_name);

	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
	if (!inst)
		return -ENOMEM;

	spawn = skcipher_instance_ctx(inst);

	crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
	err = crypto_grab_skcipher(spawn, cipher_name, 0,
				   crypto_requires_sync(algt->type,
							algt->mask));
	if (err == -ENOENT) {
		err = -ENAMETOOLONG;
		if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
			     cipher_name) >= CRYPTO_MAX_ALG_NAME)
			goto err_free_inst;

		err = crypto_grab_skcipher(spawn, ecb_name, 0,
					   crypto_requires_sync(algt->type,
								algt->mask));
	}

	if (err)
		goto err_free_inst;

	alg = crypto_skcipher_spawn_alg(spawn);

	err = -EINVAL;
	if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
		goto err_drop_spawn;

	if (crypto_skcipher_alg_ivsize(alg))
		goto err_drop_spawn;

	err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
				  &alg->base);
	if (err)
		goto err_drop_spawn;

	err = -EINVAL;
	cipher_name = alg->base.cra_name;

	/* Alas we screwed up the naming so we have to mangle the
	 * cipher name.
	 */
	if (!strncmp(cipher_name, "ecb(", 4)) {
		unsigned len;

		len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
		if (len < 2 || len >= sizeof(ecb_name))
			goto err_drop_spawn;

		if (ecb_name[len - 1] != ')')
			goto err_drop_spawn;

		ecb_name[len - 1] = 0;

		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
			     "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
			err = -ENAMETOOLONG;
			goto err_drop_spawn;
		}
	} else
		goto err_drop_spawn;

	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.base.cra_priority = alg->base.cra_priority;
	inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
	inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
				       (__alignof__(be128) - 1);

	inst->alg.ivsize = LRW_BLOCK_SIZE;
	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
				LRW_BLOCK_SIZE;
	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
				LRW_BLOCK_SIZE;

	inst->alg.base.cra_ctxsize = sizeof(struct priv);

	inst->alg.init = init_tfm;
	inst->alg.exit = exit_tfm;

	inst->alg.setkey = setkey;
	inst->alg.encrypt = encrypt;
	inst->alg.decrypt = decrypt;

	inst->free = free;

	err = skcipher_register_instance(tmpl, inst);
	if (err)
		goto err_drop_spawn;

out:
	return err;

err_drop_spawn:
	crypto_drop_skcipher(spawn);
err_free_inst:
	kfree(inst);
	goto out;
}

static struct crypto_template crypto_tmpl = {
	.name = "lrw",
	.create = create,
	.module = THIS_MODULE,
};

static int __init crypto_module_init(void)
{
	return crypto_register_template(&crypto_tmpl);
}

static void __exit crypto_module_exit(void)
{
	crypto_unregister_template(&crypto_tmpl);
}

subsys_initcall(crypto_module_init);
module_exit(crypto_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LRW block cipher mode");
MODULE_ALIAS_CRYPTO("lrw");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
64470f1b RS	2	/* LRW: as defined by Cyril Guyot in
	3	* http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
	4	*
	5	* Copyright (c) 2006 Rik Snel <[email protected]>
	6	*
6c2205b8	7	* Based on ecb.c
64470f1b	8	* Copyright (c) 2006 Herbert Xu <[email protected]>
64470f1b RS	9	*/
	10	/* This implementation is checked against the test vectors in the above
	11	* document and by a test vector provided by Ken Buchanan at
	12	* http://www.mail-archive.com/[email protected]/msg00173.html
	13	*
	14	* The test vectors are included in the testing module tcrypt.[ch] */
6c2205b8	15
700cb3f5 HX	16	#include <crypto/internal/skcipher.h>
700cb3f5 HX	17	#include <crypto/scatterwalk.h>
64470f1b RS	18	#include <linux/err.h>
	19	#include <linux/init.h>
	20	#include <linux/kernel.h>
	21	#include <linux/module.h>
	22	#include <linux/scatterlist.h>
	23	#include <linux/slab.h>
	24
	25	#include <crypto/b128ops.h>
	26	#include <crypto/gf128mul.h>
64470f1b	27
217afccf EB	28	#define LRW_BLOCK_SIZE 16
217afccf EB	29
171c0204	30	struct priv {
700cb3f5	31	struct crypto_skcipher *child;
217afccf EB	32
	33	/*
	34	* optimizes multiplying a random (non incrementing, as at the
	35	* start of a new sector) value with key2, we could also have
	36	* used 4k optimization tables or no optimization at all. In the
	37	* latter case we would have to store key2 here
	38	*/
	39	struct gf128mul_64k *table;
	40
	41	/*
	42	* stores:
	43	* key2{ 0,0,...0,0,0,0,1 }, key2{ 0,0,...0,0,0,1,1 },
	44	* key2{ 0,0,...0,0,1,1,1 }, key2{ 0,0,...0,1,1,1,1 }
	45	* key2*{ 0,0,...1,1,1,1,1 }, etc
	46	* needed for optimized multiplication of incrementing values
	47	* with key2
	48	*/
	49	be128 mulinc[128];
171c0204 JK	50	};
171c0204 JK	51
700cb3f5	52	struct rctx {
700cb3f5	53	be128 t;
700cb3f5 HX	54	struct skcipher_request subreq;
	55	};
	56
64470f1b RS	57	static inline void setbit128_bbe(void *b, int bit)
64470f1b RS	58	{
8eb2dfac HX	59	__set_bit(bit ^ (0x80 -
	60	#ifdef __BIG_ENDIAN
	61	BITS_PER_LONG
	62	#else
	63	BITS_PER_BYTE
	64	#endif
	65	), b);
64470f1b RS	66	}
64470f1b RS	67
217afccf EB	68	static int setkey(struct crypto_skcipher parent, const u8 key,
217afccf EB	69	unsigned int keylen)
64470f1b	70	{
217afccf EB	71	struct priv *ctx = crypto_skcipher_ctx(parent);
	72	struct crypto_skcipher *child = ctx->child;
	73	int err, bsize = LRW_BLOCK_SIZE;
	74	const u8 *tweak = key + keylen - bsize;
64470f1b	75	be128 tmp = { 0 };
171c0204	76	int i;
64470f1b	77
217afccf EB	78	crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	79	crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
	80	CRYPTO_TFM_REQ_MASK);
	81	err = crypto_skcipher_setkey(child, key, keylen - bsize);
	82	crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
	83	CRYPTO_TFM_RES_MASK);
	84	if (err)
	85	return err;
	86
64470f1b RS	87	if (ctx->table)
	88	gf128mul_free_64k(ctx->table);
	89
	90	/* initialize multiplication table for Key2 */
171c0204	91	ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
64470f1b RS	92	if (!ctx->table)
	93	return -ENOMEM;
	94
	95	/* initialize optimization table */
	96	for (i = 0; i < 128; i++) {
	97	setbit128_bbe(&tmp, i);
	98	ctx->mulinc[i] = tmp;
	99	gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
	100	}
	101
	102	return 0;
	103	}
171c0204	104
c778f96b OM	105	/*
	106	* Returns the number of trailing '1' bits in the words of the counter, which is
	107	* represented by 4 32-bit words, arranged from least to most significant.
	108	* At the same time, increments the counter by one.
	109	*
	110	* For example:
	111	*
	112	* u32 counter[4] = { 0xFFFFFFFF, 0x1, 0x0, 0x0 };
	113	* int i = next_index(&counter);
	114	* // i == 33, counter == { 0x0, 0x2, 0x0, 0x0 }
	115	*/
	116	static int next_index(u32 *counter)
64470f1b	117	{
c778f96b	118	int i, res = 0;
64470f1b	119
c778f96b	120	for (i = 0; i < 4; i++) {
fd27b571 AB	121	if (counter[i] + 1 != 0)
	122	return res + ffz(counter[i]++);
	123
c778f96b OM	124	counter[i] = 0;
c778f96b OM	125	res += 32;
64470f1b RS	126	}
64470f1b RS	127
fbe1a850 OM	128	/*
	129	* If we get here, then x == 128 and we are incrementing the counter
	130	* from all ones to all zeros. This means we must return index 127, i.e.
	131	* the one corresponding to key2*{ 1,...,1 }.
	132	*/
	133	return 127;
64470f1b RS	134	}
64470f1b RS	135
ac3c8f36 OM	136	/*
	137	* We compute the tweak masks twice (both before and after the ECB encryption or
	138	* decryption) to avoid having to allocate a temporary buffer and/or make
	139	* mutliple calls to the 'ecb(..)' instance, which usually would be slower than
	140	* just doing the next_index() calls again.
	141	*/
	142	static int xor_tweak(struct skcipher_request *req, bool second_pass)
64470f1b	143	{
700cb3f5	144	const int bs = LRW_BLOCK_SIZE;
700cb3f5	145	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
700cb3f5	146	struct priv *ctx = crypto_skcipher_ctx(tfm);
ac3c8f36 OM	147	struct rctx *rctx = skcipher_request_ctx(req);
ac3c8f36 OM	148	be128 t = rctx->t;
700cb3f5	149	struct skcipher_walk w;
c778f96b OM	150	__be32 *iv;
c778f96b OM	151	u32 counter[4];
700cb3f5	152	int err;
64470f1b	153
ac3c8f36 OM	154	if (second_pass) {
	155	req = &rctx->subreq;
	156	/* set to our TFM to enforce correct alignment: */
	157	skcipher_request_set_tfm(req, tfm);
	158	}
64470f1b	159
ac3c8f36	160	err = skcipher_walk_virt(&w, req, false);
aec286cd EB	161	if (err)
aec286cd EB	162	return err;
c778f96b	163
aec286cd	164	iv = (__be32 *)w.iv;
c778f96b OM	165	counter[0] = be32_to_cpu(iv[3]);
	166	counter[1] = be32_to_cpu(iv[2]);
	167	counter[2] = be32_to_cpu(iv[1]);
	168	counter[3] = be32_to_cpu(iv[0]);
64470f1b	169
700cb3f5 HX	170	while (w.nbytes) {
	171	unsigned int avail = w.nbytes;
	172	be128 *wsrc;
	173	be128 *wdst;
	174
	175	wsrc = w.src.virt.addr;
	176	wdst = w.dst.virt.addr;
64470f1b	177
64470f1b	178	do {
ac3c8f36	179	be128_xor(wdst++, &t, wsrc++);
700cb3f5	180
64470f1b RS	181	/* T <- I*Key2, using the optimization
64470f1b RS	182	* discussed in the specification */
ac3c8f36	183	be128_xor(&t, &t, &ctx->mulinc[next_index(counter)]);
700cb3f5	184	} while ((avail -= bs) >= bs);
64470f1b	185
ac3c8f36	186	if (second_pass && w.nbytes == w.total) {
c778f96b OM	187	iv[0] = cpu_to_be32(counter[3]);
	188	iv[1] = cpu_to_be32(counter[2]);
	189	iv[2] = cpu_to_be32(counter[1]);
	190	iv[3] = cpu_to_be32(counter[0]);
	191	}
	192
700cb3f5 HX	193	err = skcipher_walk_done(&w, avail);
700cb3f5 HX	194	}
64470f1b	195
700cb3f5 HX	196	return err;
	197	}
	198
ac3c8f36	199	static int xor_tweak_pre(struct skcipher_request *req)
700cb3f5	200	{
ac3c8f36	201	return xor_tweak(req, false);
700cb3f5 HX	202	}
700cb3f5 HX	203
ac3c8f36	204	static int xor_tweak_post(struct skcipher_request *req)
700cb3f5	205	{
ac3c8f36	206	return xor_tweak(req, true);
64470f1b RS	207	}
64470f1b RS	208
ac3c8f36	209	static void crypt_done(struct crypto_async_request *areq, int err)
700cb3f5 HX	210	{
700cb3f5 HX	211	struct skcipher_request *req = areq->data;
700cb3f5	212
b257b48c HX	213	if (!err) {
	214	struct rctx *rctx = skcipher_request_ctx(req);
	215
	216	rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
ac3c8f36	217	err = xor_tweak_post(req);
b257b48c	218	}
700cb3f5 HX	219
	220	skcipher_request_complete(req, err);
	221	}
	222
ac3c8f36	223	static void init_crypt(struct skcipher_request *req)
64470f1b	224	{
ac3c8f36	225	struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
700cb3f5	226	struct rctx *rctx = skcipher_request_ctx(req);
ac3c8f36	227	struct skcipher_request *subreq = &rctx->subreq;
700cb3f5	228
ac3c8f36 OM	229	skcipher_request_set_tfm(subreq, ctx->child);
	230	skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req);
	231	/* pass req->iv as IV (will be used by xor_tweak, ECB will ignore it) */
	232	skcipher_request_set_crypt(subreq, req->dst, req->dst,
	233	req->cryptlen, req->iv);
700cb3f5	234
ac3c8f36 OM	235	/* calculate first value of T */
ac3c8f36 OM	236	memcpy(&rctx->t, req->iv, sizeof(rctx->t));
64470f1b	237
ac3c8f36 OM	238	/* T <- IKey2 /
ac3c8f36 OM	239	gf128mul_64k_bbe(&rctx->t, ctx->table);
64470f1b RS	240	}
64470f1b RS	241
ac3c8f36	242	static int encrypt(struct skcipher_request *req)
64470f1b	243	{
ac3c8f36 OM	244	struct rctx *rctx = skcipher_request_ctx(req);
ac3c8f36 OM	245	struct skcipher_request *subreq = &rctx->subreq;
64470f1b	246
ac3c8f36 OM	247	init_crypt(req);
	248	return xor_tweak_pre(req) ?:
	249	crypto_skcipher_encrypt(subreq) ?:
	250	xor_tweak_post(req);
700cb3f5 HX	251	}
	252
	253	static int decrypt(struct skcipher_request *req)
	254	{
ac3c8f36 OM	255	struct rctx *rctx = skcipher_request_ctx(req);
	256	struct skcipher_request *subreq = &rctx->subreq;
	257
	258	init_crypt(req);
	259	return xor_tweak_pre(req) ?:
	260	crypto_skcipher_decrypt(subreq) ?:
	261	xor_tweak_post(req);
64470f1b RS	262	}
64470f1b RS	263
700cb3f5	264	static int init_tfm(struct crypto_skcipher *tfm)
64470f1b	265	{
700cb3f5 HX	266	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	267	struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
	268	struct priv *ctx = crypto_skcipher_ctx(tfm);
	269	struct crypto_skcipher *cipher;
64470f1b	270
700cb3f5	271	cipher = crypto_spawn_skcipher(spawn);
2e306ee0 HX	272	if (IS_ERR(cipher))
2e306ee0 HX	273	return PTR_ERR(cipher);
64470f1b	274
2e306ee0	275	ctx->child = cipher;
700cb3f5 HX	276
	277	crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
	278	sizeof(struct rctx));
	279
64470f1b RS	280	return 0;
	281	}
	282
700cb3f5	283	static void exit_tfm(struct crypto_skcipher *tfm)
64470f1b	284	{
700cb3f5	285	struct priv *ctx = crypto_skcipher_ctx(tfm);
171c0204	286
217afccf EB	287	if (ctx->table)
217afccf EB	288	gf128mul_free_64k(ctx->table);
700cb3f5 HX	289	crypto_free_skcipher(ctx->child);
	290	}
	291
	292	static void free(struct skcipher_instance *inst)
	293	{
	294	crypto_drop_skcipher(skcipher_instance_ctx(inst));
	295	kfree(inst);
64470f1b RS	296	}
64470f1b RS	297
700cb3f5	298	static int create(struct crypto_template tmpl, struct rtattr *tb)
64470f1b	299	{
700cb3f5 HX	300	struct crypto_skcipher_spawn *spawn;
	301	struct skcipher_instance *inst;
	302	struct crypto_attr_type *algt;
	303	struct skcipher_alg *alg;
	304	const char *cipher_name;
	305	char ecb_name[CRYPTO_MAX_ALG_NAME];
ebc610e5 HX	306	int err;
ebc610e5 HX	307
700cb3f5 HX	308	algt = crypto_get_attr_type(tb);
	309	if (IS_ERR(algt))
	310	return PTR_ERR(algt);
	311
	312	if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
	313	return -EINVAL;
	314
	315	cipher_name = crypto_attr_alg_name(tb[1]);
	316	if (IS_ERR(cipher_name))
	317	return PTR_ERR(cipher_name);
	318
	319	inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
	320	if (!inst)
	321	return -ENOMEM;
	322
	323	spawn = skcipher_instance_ctx(inst);
	324
	325	crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
	326	err = crypto_grab_skcipher(spawn, cipher_name, 0,
	327	crypto_requires_sync(algt->type,
	328	algt->mask));
	329	if (err == -ENOENT) {
	330	err = -ENAMETOOLONG;
	331	if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
	332	cipher_name) >= CRYPTO_MAX_ALG_NAME)
	333	goto err_free_inst;
	334
	335	err = crypto_grab_skcipher(spawn, ecb_name, 0,
	336	crypto_requires_sync(algt->type,
	337	algt->mask));
	338	}
	339
ebc610e5	340	if (err)
700cb3f5	341	goto err_free_inst;
64470f1b	342
700cb3f5	343	alg = crypto_skcipher_spawn_alg(spawn);
64470f1b	344
700cb3f5 HX	345	err = -EINVAL;
	346	if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
	347	goto err_drop_spawn;
64470f1b	348
700cb3f5 HX	349	if (crypto_skcipher_alg_ivsize(alg))
700cb3f5 HX	350	goto err_drop_spawn;
64470f1b	351
700cb3f5 HX	352	err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
	353	&alg->base);
	354	if (err)
	355	goto err_drop_spawn;
64470f1b	356
700cb3f5 HX	357	err = -EINVAL;
700cb3f5 HX	358	cipher_name = alg->base.cra_name;
64470f1b	359
700cb3f5 HX	360	/* Alas we screwed up the naming so we have to mangle the
	361	* cipher name.
	362	*/
	363	if (!strncmp(cipher_name, "ecb(", 4)) {
	364	unsigned len;
64470f1b	365
700cb3f5 HX	366	len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
	367	if (len < 2 \|\| len >= sizeof(ecb_name))
	368	goto err_drop_spawn;
64470f1b	369
700cb3f5 HX	370	if (ecb_name[len - 1] != ')')
700cb3f5 HX	371	goto err_drop_spawn;
64470f1b	372
700cb3f5	373	ecb_name[len - 1] = 0;
64470f1b	374
700cb3f5	375	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
616129cc CJ	376	"lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
	377	err = -ENAMETOOLONG;
	378	goto err_drop_spawn;
	379	}
d38efad2 CJ	380	} else
d38efad2 CJ	381	goto err_drop_spawn;
700cb3f5 HX	382
	383	inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
	384	inst->alg.base.cra_priority = alg->base.cra_priority;
	385	inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
	386	inst->alg.base.cra_alignmask = alg->base.cra_alignmask \|
20a0f976	387	(__alignof__(be128) - 1);
700cb3f5 HX	388
	389	inst->alg.ivsize = LRW_BLOCK_SIZE;
	390	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
	391	LRW_BLOCK_SIZE;
	392	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
	393	LRW_BLOCK_SIZE;
	394
	395	inst->alg.base.cra_ctxsize = sizeof(struct priv);
	396
	397	inst->alg.init = init_tfm;
	398	inst->alg.exit = exit_tfm;
	399
	400	inst->alg.setkey = setkey;
	401	inst->alg.encrypt = encrypt;
	402	inst->alg.decrypt = decrypt;
	403
	404	inst->free = free;
	405
	406	err = skcipher_register_instance(tmpl, inst);
	407	if (err)
	408	goto err_drop_spawn;
	409
	410	out:
	411	return err;
	412
	413	err_drop_spawn:
	414	crypto_drop_skcipher(spawn);
	415	err_free_inst:
64470f1b	416	kfree(inst);
700cb3f5	417	goto out;
64470f1b RS	418	}
	419
	420	static struct crypto_template crypto_tmpl = {
	421	.name = "lrw",
700cb3f5	422	.create = create,
64470f1b RS	423	.module = THIS_MODULE,
	424	};
	425
	426	static int __init crypto_module_init(void)
	427	{
	428	return crypto_register_template(&crypto_tmpl);
	429	}
	430
	431	static void __exit crypto_module_exit(void)
	432	{
	433	crypto_unregister_template(&crypto_tmpl);
	434	}
	435
c4741b23	436	subsys_initcall(crypto_module_init);
64470f1b RS	437	module_exit(crypto_module_exit);
	438
	439	MODULE_LICENSE("GPL");
	440	MODULE_DESCRIPTION("LRW block cipher mode");
4943ba16	441	MODULE_ALIAS_CRYPTO("lrw");